use experimental go json v2 library (#35392)

details: https://pkg.go.dev/encoding/json/v2

---------

Co-authored-by: techknowlogick <matti@mdranta.net>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

tests/integration/api_packages_swift_test.go

@@ -318,7 +318,7 @@ func TestPackageSwift(t *testing.T) {
 			AddBasicAuth(user.Name)
 		resp = MakeRequest(t, req, http.StatusOK)
 
-		assert.Equal(t, body, resp.Body.String())
+		assert.JSONEq(t, body, resp.Body.String())
 	})
 
 	t.Run("PackageVersionMetadata", func(t *testing.T) {